Control system



Oct. 13, 1942. P. F. HlvlzRs CONTROL SYSTEM Filed June 6, 1938 3 Shets-Sheet 1 Oct; 13, 1942. P; F. sl-uvERs 2,298,810

CONTROL SYSTEM v Filed June 6, 1958 3 Sheets-Sheet 2 m3 I ml liiShivws I M MM Gnome;

' Oct. 13,1942. P, F; s w s 2,298,810

- I CONTROL SYSTEM Filed June 6, 19:58 3 Sheets- Sheet s a condition responsive device 7 moved or a combined pensator with its cover and Patented Oct. 13, 1942 NITElj STATES PATENT vo mes common SYSTEM Paul F. Shivers, Wabash, Ind assignor to Minneapolis-Honeywell Regulator Company, Minneapolls, Minn., a corporation of Delaware Application June 6, 1938, Serial No. 211,997 13 Claims. (crest-s This invention 'relatesin general to air conditioning and is more particularly concerned with automatic controls for air-conditioning systems.-

'It is an object of this invention to automatic control system for automatically placing a cooling-device in operation when cooling is-required, for automatically placing an indirect heating device in operation when a slight amount of heat is required; and for placing a direct heating device in'operation when a large amount of heat is required for maintaining the space comfortable.

A further object of this invention is to provide a system of this type in which the standard of temperature maintained during the cooling season is varied automatically-ior providing proper comfort conditions within the space.

A further object 01' this invention is the provision of a pneumatic control arrangement for adjusting the standard of the condition maintained by a pneumatic type of controller in accordance with a pluralityoi' conditions Still another object of this invention is the provision of a pneumatic adjusting arrangement for which is operable over a wide range of values.

Other objects oi-this invention lie in various structural details of the control apparatus and tem.- These objects will become apparent from the following description and the appended claims. I I

For a full disclosure of my invention, reference is made to the following detailed description and to the accompanying-draWing 8,1n which:

Figure 1 illustrates diagrammatically. a complete control system embodying thenovel features of my invention;

provide an to cause air to flow into the-chamber 2 through an opening 2 and to flow through the chamber 2, this fan discharging into a duct 2 which distributes the conditioned air throughout the car.

The fan 2 is driven by a motor I under the control of a manual switch 8. vLocated within the to a source of steam or other suitable heating me dium. The valves l2 and II are controlled in unisonby means of an air electric relay generally indicated as IT. This relay is diagrammatically illustrated as comprising a bellows l8 which actuates a shaft I2 carrying member 20 for actuating switch members 2| and 22 which cooperate with in various subcombinations of the'complete systil contacts 22,' 22, 22, and 22. biased by means of asprlng 21.. Upon a decrease in pressure within bellows ill, the shaft I! will move to the right while the switch members 2| and 22 will remain'in engagement with contacts and 22, respectively, due to the action or a' spring 22. when bellows I2 contracts sufllciently. to cause the switch members 2| and 22 to cross, the center line of spring 22, this spring will cause snapping of members 2| and 22 into engagement with contacts 22 and 22. ,Upon an increase inv pressure within bellows l2, the opposite action will take place, namely, the switchmembers 2| and 22 will snap into engagement with the con- Figure 2 is a front view with thecovcrs re- A I space temperature and relative humidity controller; 1

Figure 3 is a section taken on line 2-2 of V Figure 2;

Figure 4 is a section Figure 2; I Figure 5 is an elevation of the outside comdisc type thermostatic element removed, and Figure 6 is a section taken on line 2-2 of Figure 5.. n

Reierring to Figure-1, reference character I indicates diagrammatically a railroad car which is provided with an airconditioning chamber 2 located adjacent the'ceiling or the vestibule 2.

fanl is locatedwithin the chamber 2 and acts taken on line 4-2 of tacts 22 and 22, as shown.

The contacts 22 and 22 are connected together and'to-a line wire 22, while the other line wire "is connected to the common terminals 01' the control-valves l2 and H, as shown. The contact 22 is connected by wire 22 to the opening terminals 01' valves l2 and i2, while contact 22 is connected by wire 22 to the closing terminals of these valves.- when the pressure applied to the bellows i2 is, above'a predetermined value, the switch members 2| and 22 will assume thepositions shown which completes-a circuit from line wire 22, contact 22,'switch members 2| and 22', contact 22, wire 22, to the closing terminals of valves l2 7 and ll. When the pressure in bellows I2 is below this predetermined value, the switch members 2| and 22 will engage the contacts 22 and 22 for completing a circuit through'the opening termi- The bellows I8 is,

nals 01 valves i3 an M. It should, therefore, be

value, the .valves i3 and i4 will be closed for I thermostat is diagrammatically illustrated in placing the direct heaters ii. and I! out of operation.-

The heating coil 9 is connected by pipe 34 to a valve 35 which controls the flow of steam'or other suitable heating medium to coil 9; This valve is preferably actuated by means of an airelectric motor. 36; This air electric motor is diagrammatically illustrated as comprising a reversible direct current motor having an armature 31 and series fields 38 and 89. The armature 37 .actuates ran-operating shaft 48 through a gear train (not shown) and the shaft 40, in turn, ac-

1 tuates the valve 85 by means of pinion 4i and rack 42. It will be understood that when the field coil 38 is energized the armature 37 willrotate in one direction, while when the field coil 39 is energized the armature Bl will rotate in the opposite direction.

Selective energization of the coils 38 and 39 is controlled by means oi a relay 43. This relay consists of a bellows 44 which actuates an insulated contact carrier 45 which carries contacts 46' and 41 cooperating with a contact 48, this contact being carried by an insulated nut 49 threaded upon a portion of the operating shaft 40. l

When the pressure within the bellows 44 is increased, the contact carrier 45 will be shifted to theleft thus bringing contact 41 into engagement with contact 48. This will complete a circuit from wire 50 through armature 8i, field coil89, wire contacts 41 and 48, to wire 52, which willcause rotation 01 the shaft 40 in a direction or closing valve 85. This rotation of shaft 48 will cause movement of nut 49 to the left, thus tending to disengage contact as from Figure 1 as comprising a bimetallic element 86 which is adapted to actuate valve members 61,

68, and 69 which cooperate with bleed ports or nozzles 18, ii, and I2, respectively. The valve member 61 is pivoted to a movable support 13,

while the valve members 68 and 69 are provided with stationary pivots i4 and 15. The movable support 13 preferably comprises a diaphragm structure consisting of an outer bellows l6 and an inner concentric bellows ll, this providing two separate chambers in said diaphragm structure which are out of communication with each other.

'ti is attached, reducing valves 82 and 83 and filter 84 being interposed in this main. Connected to the main 8| by means of pipe 85 is a restriction 86, the outlet of which is connected to port ill and valve motor ti by pipes 81 and ti Also connected to the main 8i by pipe 89 is a restriction 90, and the outlet of this restriction is .-connected-by pipes 9i and 92 to the port ii and to the valve motor 36. Also connected to main 8! is a restriction 93, and the outlet of this restriction is connected by pipes 94 and 95 to the port 12 and air-electric relay i1. By this arzangement, the valve member 61 and port 10 control the-pressure applied to valve motor 8i, the valve member 68 and port 1i control the pressure applied to valve motor 36, and the valve member 69 and port 12 control the pressure applied to therelay I1.

The valve members 81, 68, and 88 are arranged relatively to their'valve portsso as to provide sequential operation of the valve motors 6i and 38 and the relay i1. .When the space temperacontact 41. When the closing movement of valve upon decrease in pressure within bellows 44, the

contact 48 will engage contact 48 for causin movement or the valve towards open position an amount proportionate to the decrease'in pressure.

Reference character 55 indicates an ice bunker or other cooling device which may contain a coil 58, the outlet or which is connected by pipe 5! to the inlet of cooling coll it in the conditionin chamber 2. The outlet of cooling coil it is connected by a pipe 58 to the inlet oil pump 58. This pump, in turn, is connected to a control valve 80 at the inlet of coil 88. The valve 6i? may be actuated by means of an air-electric motor 3i which may be of the same type as the motor 35 for valve 35. However, the motor 6i .is arranged reversehr to that of motor 36 so as to cause the valve 60 to be opened upon increase in pressure applied to motor 6i. The pump 58 may be driven by means of an electric motor 88 under the control of a manual switch 44.

ture is at a low value, the bimetallic element 86 will through abutment members 61a, 68a, and 69a push valve members 61, 68 and 69 away from their respective ports. As the space temperature increases from this value, the center of the bimetallic element 66 will rise, this permitting upward movement of the valve members 61, 68, and 8 59 under the action of individual springs. Upon this rise in temperature, the valve member 69 will first engage port 12, while the valve members 6? and 68 remain spaced from their respective ports. Upon continued rise in temperature, the valve member 88 will cover port ii while port it will remain uncovered by valve member 67,

and upon continued rise in temperature, the valve member ill will finally cover valve port is.

Assuming now that the space temperature is at a high value, such as F., the valvemembers'6'h 68, and 69 will all cover their respective ports. Due to the closing of port 12 by valve member 59, maximum pressure will be built up within the bellows i8 and this will cause the relay i? to assume the position shown which causes the valves l3. and i4 to be closed for placing heaters ii and i2 out of operation. Due to closing of port. H by valve members 88, maximum pressure will be applied to bellows 44 of the airelectric motor 36, this causing this motor to drive valve to completely closed position. Also due to port 10 being closed by valve member 61, maximum pressure will be applied to valve motor ii to open valve 88 wide thus providing a maximum amount oi cooling for the space. It will therefore bev seen when the space temperature is at thislhigh value, the supply of heating medium to the heating coils 0, II, and II will be"cut oil and the supply of coolingmedium to the cooling coil I will be at a maximum. Upon decrease in space temperature, the valve member 01 will be shifted slightly away from port I0 thus increasing the rate of bleed from this port which deraise the temperature maintained within the car as outside temperature increases in order to prevent the space from feeling too cool to the occutions in space relative humidity for thereby com-' pensatlng for the eifect of relative humidity 1 creases the pressure applied to valve motor 0|.

This will cause the valve motor 0| partially to close valve 00 for decreasing the supply of cooling fluid to the cooling coil I0. Upon still fur- I ther fall'in-temperature, the valve member 61 will be shifted away from port I0 suiliciently for providing maximum bleed through port II which causes substantially atmospheric pressure to be applied-to motor 0|, thus causing this motor to shut the valve 00 completely. At this time; valve members 08 and 09 will remain in engagement with their respective ports II and I2 for main- As the temperature within the car falls to a value at which heating is required, for instance 70 F., the valve member 00 will begin. moving away from port II due to the action of bimetallic element 66. Atthis time, the valve member 01 is substantially spaced from port I0 and thus the cooling valve 60 is completely closed. Due to valve member 68 shifting away from port .II. air

will bleed through port II thus reducing the pressure applied to bellows 40 of motor 00. This will cause motor 36 to open the valve 00 for sup- I plying heating medium-to the heating coil 5-. At

this time, the position of the valve 05 will be graduatingly controlled by valvemember 00 for maintaining the space temperature substantially constant, the valve being opened as the space temperature decreases and being closed as the space temperature increases. Also at this time,

the valve member 69 will remain engaged with port I2 for supplyingmaximum pressure to relay II which maintains valves "and I0 closed.

As the weather becomes moresevere, the heating coil 9 will not be capable of maintaining the car sulliciently warm even when the valve 35 is wide open. This will result in the space temperature continuing to fall. When this space temperature falls to, a predetermined minimum value, such as 68 F., the valve member 09. will disengage port I2 for reducing the pressure applied to the bellows I0 of relay I'I. This reduction in pressure will cause contraction of bellows I0 for shifting-switch members II and 22 into engagement with contacts 23 and 20, thereby opening valves I0 and I0 thus supplying heating medium to the direct heating coils II and II.

From the description thus far, it should be apparent that when the space temperature is high enough to. require cooling, the position of valve 0| will be adjusted for maintaining the'desired space temperature. As the space temperature falls, the valve 8i will be closed and upon a fall in space temperature to a value requiring heating, the valve 30 will be opened while the valves I3 and. I0 remain closed. If this is incapable of maintaining the desired space temperature, the

valves I 3 and I4 will finally be opened. It will be apparent that upon rise in temperature the various devices will operate inreverse order.

pants at this time. It is also desirable to vary the space temperature in accordance with variachanges upon human comfort. In order to obtain these results, an outside temperature compensator I00 and an inside humidity compensator IOI are provided, these compensators being arranged to vary the pressure applied to the ad- Justing diaphragm structure of valve member 01. Referring to the outside temperature compensator I00, this device'may consist of a bimetallic element I02 which actuates a valve member I03 1 cooperating with a port I00. This port I00 is connected by pipes I05 and I06 to the interior of bellows I1 and also to the restriction I 01 which is connected to the air supply main 8|. As the outside temperature increases, the bimetallic ele- .ment I02 will permit valve member I03 to approach port I00 which will restrict the rate of bleed through this port and consequently increase the pressure applied to the interior of bellows I1.

' This will cause expansion of the bellows structure and upward movement of fulcrum I3, this having the eifect of shifting-valve member away from port I0 for decreasing the amount of cooling performed. This will result in the space temperature increasing, and in response to this increase in space temperature the bimetallic element 60 will permit valve member BI to approach port I0 for thereby increasing the amount of cooling fluid supplied to the cooling coil I0. When the resulting increase in cooling fluid supply is sufllcient for preventing further temperature increase, the space temperature will remain constant at this higher value. It should, therefore, be seen that as outside temperature increases, the compensating thermostat I00 will adwith respect to the port is sufiicient to permit the bleeding to reach its maximum value. For

instance, with this type of controller when the.

valve member is shifted only .001 inch from the port, the bleeding through the port will be at pressure applied to bellows I 08.

amaximum. Due to the extreme sensitivity of this type of pneumatic control, it is not suited ior use in a compensating type of instrument wherein the range of the instrument must be very wide. In order "to widen out the range of the instrument so as to be suitable for compensating purposes, a bellows I 08 is provided for shifting the fulcrum I09 of the valve member I03. This bellows I08 is connected to the pipe I05 so that it is subjected to the pressure established by thevalve member I03. Assuming that outside temperature increases, the valve member I03 will be shifted towards its port by the thermostatic element I02, this increasing the pressure applied 'to the bellows l1 and also the to'this increase in pressure,v the bellows I08 will expand thus raising the pivot I09 of valve member I03 which has the efiect of causing it to recede from port I00. In other words,-the bellows I 08 opposes-the'action of the thermostatic element I02 and provides what may be termed a partial follow-up movementtending to return In response the valve member I03 to its original position with respect to port I04. Due to this action of bellows I08, a given downward movement of bimetallic element I02 will have less effect on the position of valve member I03 relative to valve port I 04, than it would have if the bellows I08 were not'present. The bellows I08 therefore acts to widen out the range of the thermostat I so that it is suitable for adjusting the thermostat 65 over a wide range of outdoor temperatures. Y

Referring to the humidity compensator IIlI, this instrument is shown diagrammaticallyin Figure 1 as comprising a valve member H0 co- II3 are also connected to a restriction H4 which is' connected to the air supply main BI. Valve member III] is fulcrumed to a bellows H5 which has the same function as the bellows I08 of thermostat I00. This valve is also actuated by means of a humidity responsive device IIG.

Assuming a decrease in relative humidity within the space, the humidity responsive device II6 will shrink, thus causing valve member IIO to approach port III, this raising the pressure in the space between bellows I5 and I! of the adjusting diaphragm structure. This will cause upward movement of the pivot'l3 of valve member 81 thus causing valve member 51 to recede from port I0 for decreasing the pressure applied to valve motor SI thus decreasing the amount of cooling fluid supplied to cooling 'coil thermostatic element 86 will cause valve member 61 to approach port I0 for increasing the supply of cooling medium. When the space temperature has risen to a point wherein the cooling fluid increase is suillcient for preventing further increase in temperature, the space temperature will remain constant at this higher value. It will, thereiore, be seen that a decrease in relative humidity will adjust the thermostat 65 in a manner to maintain a higher space temperature. This adjustment of the space thermostat 65 in accordance with variations in humidity provides for maintaining a predetermined effective temperature within the space.

From the foregoing description, it will be apparent that the control system just described automatically controls the temperature within the space during both summer and winter. During the summer, the heating coils 9, I I and I2 are automatically placed out of operation and the amount of cooling fluid supplied to the cooling coil I0 is controlled in order to maintain a predetermined effective temperature within the space, the standard of effective temperature maintained being varied in accordance with variations in outdoor temperature.

Referring now to Figures 2, 3, and 4, these figures indicate the details of construction of the space thermostat and the humidity compensator It". If desired, the thermostat 65 and compensator IIII may be mounted in a single casting or-base I20. This casting I26 is iormed to provide a circular casing I2I for housing the various parts of the thermostat. The casing I2I is open at its outer end and is threaded to receive a ring I25, into which ring the thermostatic element or.disc 86 is held by means of a snap I31 which extends through the slot I36.

ring I24. Located about the periphery of the casing I2I are bosses 10a, Ila, and 12a, the boss 10a of which is shown in section in Figure 3. This boss contains an air passage I25 and is formed to provide a second passage I26 communicating with'the passage I25 and which extends rearwardly, the valve port member I0 being located therein. Aplug I2I is provided at the end of passage I26 for permitting access from the exterior of the instrument to the port member 10. It will be understood that bosses Na and 12a are similar to boss 10a and provide air connections to the ports II and I2 (Figure 1). Located within the casing I2I is the diaphragm structure formed of bellows I6 and 11. Each of these bellows, it will be noted, is secured to the rear wall of easing I21 and also to a bellows head I28 which carries a U-shaped bracket I20. This bracket I29 carries the pivot I3 for the valve member 61 which extends from this pivot upwardly and rearwardly to the valve port I0. This valve member is provided with the abutment member 61:: for engaging the thermostatic disc 06.

Reference character I30 indicates a spring member for biasing the bellows or diaphragm structure towards contracted position. This spring member is secured at its upper end by rivets I3I to a boss I32 and extends downwardly into the bracket member I29. In order to provide adjustment of the spring member I30. a collar I33 is secured to the base I20 by means of a bolt I34. and nut I35. This bolt IM passes through a slot in the base member I20 which runs parallel with a slot I38 in the spring member I30. By loosening the nut I35, the collar I33 may be shifted parallel to the spring member I80. The collar I33 also receives an adjusting screw By turning the adjusting screw I31, the tension of the spring may be adjusted as desired, and by shifting the collar I35 within its range of movement, the spring rate may be varied as desired for obtaining the desired movement of the diaphragm structure for a given change in pressure,

therein. In order to limit the degree or contracmember which is secured to a boss It! in casin I2I by means of screws M2. This bracket member is formed to provide the pivot It for the valve member 00. This valve member is located behind the. valve member b! and extends across the center of easing I2I to its valve port II. The

valve member 00 is similarly arranged, its pivot being provided by the bracket member M6. Each of the valve members t'l, 68, and 69 are provided at their respective pivots with springs I46, I61. and It! for urging these valve members towards their respective ports.

The arrangement just described. it should be noted, provides for housing all three valve members compactly within a small space and further provides for sealing all of the working parts of the instrument ina closed chamber, thus preventing tampering with the instrument and also preventing dirt from reaching the various working parts; By turning the ring I28 which supports the bimetallic disc 8%, the disc 68 may be moved inwardly or outwardly relative to the various valve members, thereby providing for an initial adjustment of the instrument. This ring lock screw I50. By removing the plugs I21, ac-

cess may be had to the various valve ports and their positions may be varied by turning them with a screw-driver inserted through the access p nin soperating sequence of the thermostat.

Referring to the'humidity compensator IOI, this device may comprise a bracket member II which is secured to the base member 'I by means of posts I52 and screws I53. This bracket member is provided with inwardly extending ears I50 and I55. Bracket member I5I also supports'a stud I56 upon which is rotatably mounted a drum I51. This drum I51 is provided with rollers I58, I59, and I60 upon which is mounted a humidity responsive elementc'onsisting of a plu-n rality of strands of hair I8I, these strands being secured at one end to the drum I51 at I62, and being secured at their other ends to a clamping member I 63 attached to an adjusting screw I66 located in the ear I55 of bracket member I5I.

This adjusting screw I64 is provided with av nut I65, rotation of which causes axial movement'of the screw I64. A spring I66 is attached to the ear I55 and urges the adjusting screw I60 in a direction for retaining the nut I65 against the ear I55. A spring ,I61- is connected between the ear I54 and the drum I51 for urging rotation of the drum I51 in a counter-clockwise direction,

this acting to maintain ;the strands I6I taut.

This provides for adjustment oi the Referring now to Figures 5 and 6, these figures illustrate a preferred construction for the outside compensator I00; This outside compensator may include a base, I85 which provides an openv ended cylindrical chamber I86; the open end thereof having fitted thereinto a ring I81. This ring I81 carries the bimetallic element or disc I02, thisdisc being' secured into the ring I81 by -means of a snap ring I88. The bellows I08 of this instrument is secured to the base I85 and this base I05 is drilled out to provide an an: passage I88 which communicates with a passage I80 leading to the bleed port member I04. The bellows I08 carries a U-shaped bracket I9I supporting the pivot I09 for the valve member I03. A spring I92 is provided for urging the valve member I08 towards the bleed port I04. The bellows I08 also is provided with a spring I93 which is secured to a boss I94. Also secured to the boss I86 is a bracket I95 which carries an adjusting screw I86 for adjusting the tension of spring I 80.

From the foregoing description, it will be apparent that I have provided a control system and control instrumentalities for automatically maintaining the temperature within a conditioned spaceat proper values during the entire year. While I have shown and described my in vention as applied toa railroad car air condi tioning system, it will be understood that the invention is not limited to applications of this With the arrangement just described. as the relative humidity increases, the strands I6I will increase in length and this will permit counterclockwise rotation of the drum I51 by the spring I61. Upon a decrease in humidity, the strands drum I51 in the opposite direction against the action of spring I61.

The bellows II5 of this controller may be located in the base I20, this base being drilled out as at I 68 for providing a passage placing the interior of the bellows II5 into communication member I12which provides a pivot I14 for-the type but may be applied to other air conditioning applications. Inasmuch as many variations of my invention will occur to those skilled in the art, I desire to be limited only by the scope of the appended claims.

' I6l will shrink and this will cause rotation of I I claim as my invention: I .1. In a compensated efiective temperature con- 'trol system, in combination, a space thermostat standard of temperature maintained thereby, an

outside temperature responsive compensating thermostat including a first valvedevice for varying ,the pressure applied to said diaphragm means, a humidity compensating device includvalve member IIO which extends from this pivot to the port II I, a spring I15 being provided for urging this valve member against the valve port. The bellows II5 may also be provided with a spring member I16 which is securedto a suitable boss on.,base I20 by screws I11 and which extends into the bracket member I12. This-spring I16 may be provided with an adjusting screw I18 for varying the spring tension. Anadjusting screw I19 may also be provided in the base I20, this adjusting screw extending into the interior of bellows II5. This adjusting screw provides a stop for limiting the collapsing movement of the belows I5. I j

The valve member H0 is provided with an extension I80 which cooperates with a pin I8I secured to the drum I51. This arrangement provides for movement of valve member IIO upon rotation of the drum I51. Thus when the relative humidity increases and drum I51 rotates in a counter-clockwise,direction, the pin I8I will move downwardlyiFigure 2) for shifting valve member IIO away from port III. Upon a decrease in relative humidity the opposite action will take place.-

ing a second valve device forvarying the pressure applied to said diaphragm means, and differential widening means for the temperature and humidity compensating devices, comprising pressure responsive devices responsive topressure applied to said diaphragm means tending to oppose movement of said valve devices.

2. In a compensated eifective temperature control system, in, combination, a space thermostat including a control member actuated by a thermostatic element, diaphragm means for adjusting said space thermostat in a manner to vary the standard of temperature maintained thereby, said diaphragm means including first and second diaphragm chambers out of communication with each other, an outside thermostat connected to said first chamber for varying the pressure in said iirst chamber in accordance with variations in outside temperature, and means influenced by the space relative humidity connected to said second d aphragm chamber for varying the pressure in said second chamber in accordance with variations in space relative humidity.

3. In a compensated effective temperature conmostatic element, diaphragm means for adjusting said space thermostat in a manner to vary the standard of temperature maintained thereby, said diaphragm means including first and second diaphragm chambers out of communication with each other, an outside thermostat including a valve device for varying the pressure applied to one of said chambers, diflerential widening means responsive to the pressure created by said valve device for adjusting said outside thermostat in a manner tending to oppose movement of said valve device, means influenced by space relative humidity and including a valve device for varying the pressure applied to said other chamber, and difierential' widening means responsive to the pressure created by said last mentioned valve device for adjusting said space relative humidity influenced means in a manner tending to oppose movement of, said last mentioned valve device.

4. In a controller for a system of the class described, in combination, a casing providing a chamber, said casing being formed with an opening, a thermostatic element comprising a disc covering said opening, a plurality of valve ports in said chamber, a plurality of lever arms in said chamber, said lever arms being iulcrumed at spaced points and cooperating with said valve ports, means for actuating said lever arms in unison with movements oi said thermostatic element, and a diaphragm structure associated with one of said lever arms for adjusting the fulcrum thereof.

5. In a-controller for a system of the class described, in combination, a casing providing a chamber and formed with an opening, a thermostatic element comprising a disc covering said opening, a plurality of valve ports in said chamber, a plurality of lever arms in said chamber, said lever arms being fulcrumed at spaced points and cooperating with said valve ports, means for actuating said lever arms in unison with movements of said thermostatic element, a diaphragm structure associated with one of said lever arms for adjusting the fulcrum thereof, a

spring for biasing said diaphragm structure, and

6. In a controller for a system of the class described, in combination, a casing providing a chamber and formed with an opening, a thermostatic element comprising a disc covering said opening, a valve port in said chamber, a lever arm fulcrumed in said chamber and cooperating with said valve port, said lever arm being actuated in unison'ewith movements of said thermostatic element, and a diaphragm structure associated with said lever arm for adjusting the fulcrum thereof.

7. In a controller for a system of the class described, in combination, a casing providing a chamber and formed with an opening, a thermostatic element comprising a disc covering said opening, a valve port in said chamber, a lever arm fulcrumed in said chamber and cooperating with said valve port, said lever arm being actuated in unisonwith movements of said thermostatic element, a diaphragm structure associated with said lever arm for adjusting the ful- 8. In a control system foran air conditioning system having direct heating means,

indirect heating means and cooling means, the combination of, first pressure actuated consaid valve devices in sequencepin a manner to place said cooling means out .of operation, to place said indirect heating means into operation, and to place said direct heating means in operation upon fall in temperature, diaphragm means for adjusting said first valve device, said and means influenced by space relative humidity diaphragm means including two chambers out of communication with each other, means responsive to outside temperature for controlling the pressure applied to one of said chambers,

for controlling the pressure applied to the other of, said chambers. r

,9. In a control system for an air conditioning system having direct heating means, indirect heating means and cooling means, the combination of, first pressure actuated control means for controlling said cooling means, second pressure actuated control means for controlling said indirect heating means, third pressure actuated control means for controlling said direct heating means, a first valve device for controlling said first pressure actuated control means, a second valve device for controlling said second pressure actuated control means, athird valve device forcontrolling said third pressure actuated control means, a single thermostatic element for actuating'all of said valve devices in sequence ina manner to place said cooling means out of operation, to place said indirect heating means into operation, and to place said direct heating means in operation upon tall in temperature, diaphragm means for adjusting said first valve'device, and

condition responsive means for varying the pressure applied to said diaphragm means to thereby vary the standard of temperature maintained in said space when said cooling means is in operation.

- 10. In a control system for an air conditioning system having direct heating means, indirect heating means and cooling means, the combination of, first pressure actuated control means for controlling said cooling means, second pressure actuated control means for controlling said indirect heating means, third pressure actuated control means for controlling said space heating means, a first valve device for controlling said first pressureactuated control means, a second valve device for controlling said second pressure actuated control means, a third valve device for controlling said third pressure actuated control means, and a single thermostatic element for actuating all of said valve devices in sequence in a manner to place said cooling means out of operation, to place said .indirect heating means into operation, and to place said direct heating means in operation upon fall in temperature.

11. In a. controller of the class described, in combination, a casing providing a chamber and formed with an opening, a thermostatic element comprising a disc covering said opening, valve means in said chamber including a valve port trol means for controlling said cooling means, 7

and a valve member, a lever arm for operating said valve means, said lever arm being actuaated about a fulcrum in unison with movements spring.

} 2,298,810 a or said thermostatic element, and diiterential widening means for said controllergsaid diil'erential widening means comprising a diaphragm subjected to the pressure established by said valvemeans and acting upon'the fulcrum of said valve lever in amanner tending to oppose rotation thereof bysaid thermostatic element.

12. In a controller oi'the class described. in combination, a casing providing a chamber and formed with an opening, a'thermostatic element comprising a disc covering said opening, valve means in said chamber including a valve port and a valve member, a lever arm for operating said valve means, said lever armbeing actuated about a fulcrum in unison with movements 0! said thermostatic element, diirerential. widening means for said controller, said diilerential widening acting .upon the fulcrum of said valve lever in a manner tending to oppose rotation thereof by said thermostatic element, a spring for biasing said diaphragm, and means for adjusting said I means comprising a diaphragm subjected to the v pressure established by said valve means and or said chambers.

prising a first chamber and a second. chamber out of communication with each other for ad- Justing the 'control point of said controller, means including a valve device for varying the pressure in the first of said chambers, an element responsive to a condition affecting the heat content of the gas for actuating said valve device, differential widening means responsive to the pressure created by said valve device for attenuating movement or said valve device with respect to movement of said element. and means responsive to the load on the system for varying the pressure in the second of said chambers-in dependently of the pressure existing in the first PAUL F. srnvnns. 

